A cosmic window to Fundamental Physics: Primordial Non-Gaussianity and beyond

The largest scales of the Universe serve as a probe of fundamental physics such as the origin of cosmic structure and general relativity. Even though there is a growing consensus that cosmic inflation provides a powerful explanation for the origin of the cosmic large-scale structure (LSS), the landscape of competing inflationary models is huge. One of the main observables which can further constrain the range of currently allowed models of inflation is primordial non-Gaussianity (PNG), parameterized through fNL. Currently the tightest constraints on PNG come from the cosmic microwave background (CMB) bispectrum measured by the Planck collaboration. However, in the future, we expect to further tighten the constraints and reach, for example, a σ(fNL)<1 for the local type of PNG by studying the largest scales of the Universe where PNG would have left an imprint of a scale-dependent bias.

Synergies between different cosmological surveys will result in unprecedented measurements of the largest scales through multi-tracer methods, which will then enable us to reduce the effects of cosmic variance and significantly improve the constraints on PNG. At such scales, light cone effects (a.k.a. GR effects) also arise, which while providing complementary constraints on gravity, can potentially bias the measurements of PNG if not modeled consistently.

With upcoming Stage IV LSS experiments such as Euclid, SKA, DESI, SphereX and LSST, we will soon be ready to explore the Universe on gigaparsec scales, but this will require us to understand, with high accuracy, observational systematic effects which could a priori bias the clustering measurements.

Future Stage IV CMB experiments will also contribute, independently, to reducing the uncertainties on PNG, constraining also non-local types of non-Gaussianity through the CMB bispectrum. CMB lensing can also be combined with other LSS probes using the multi-tracer technique.

Furthermore, with the advent of gravitational wave (GW) interferometers, we will be provided with the possibility of measuring PNG through a completely new window and over a different frequency range. In particular, recent studies predict that appreciable levels of non-Gaussianity could be detected both in ground-based interferometers like LIGO-Virgo-Kagra and from space with LISA.

The aim of this workshop is to bring together world experts on primordial non-Gaussianity and other ultralarge-scale effects with different perspectives in order to prepare for the next generation of experiments. Potentially, the new experimental era will take us to the σ(fNL)<1 level, enabling us to differentiate between different families of inflationary models, e.g. single field versus multi-field inflation.

poster_congreso.pdf